The invention is related to device enclosures and particularly to controlling static electricity generated by the insertion and removal of devices in the enclosure.
A RAID array (redundant array of independent disks) functions as one large logical mass storage device for storing data in a computer system. The actual array is a physical set of mass storage devices--most commonly hard disk drives. According to some prior art implementations, each physical disk drive device resides within an array enclosure, and can be separately inserted and removed. Some implementations, such as the model BA350 modular storage shelf from Digital Equipment Corporation, allow "hot swapping" of single devices to and from the array--that is, disk drives can be inserted into or removed from the array enclosure during operation of the array.
The Digital Equipment Corporation model BA350 modular storage shelf enclosure is shown in FIG. 1. The disk drive devices 10 of the array reside within modular device enclosures 12 having guide rails 14 which are designed to slide along opposing inward facing ribs 16 in the array enclosure. The guide rails 14 and ribs 16 guide the device 10 toward a backplane 18 at the back of the array enclosure 20, where a connector on the device mates with a backplane connector. As can be seen, the ribs 16 and structural ribs 17 are protrusions extending from the bottom and top surfaces of the enclosure 20 toward the device 10.
It has been discovered that such array enclosures are subject to static electricity problems. The continual sliding of devices along the rails of the array enclosure causes static charges to build up on the inward facing protruding ribs 16 and 17. Then, when a device contacts the backplane connector, thereby providing a discharge path, an electrostatic discharge (ESD) occurs at the shortened air gap between the ribs and the sliding device. This ESD can cause electrical component failures on the device itself. These ESD problems are particularly onerous in a "hot swap" environment where disk devices are continually inserted into and removed from the array enclosure. It is desirable, therefore, to provide an array enclosure which protects the devices installed therein from the effects of ESD.